I'm getting errors while the JDBC module is compiled because the code directly accesses attributes from the _db object, which was recently changed from SQLClient * to id (see attached log).
Incidentally, I think changing the _db attribute from SQLClient * to id to accommodate either a SQLClient or an SQLClientPool object is bad style. There should be a formal protocol (perhaps called SQLClient) to collect the common methods that should be supported by the _db object. I tried doing that, but then stopped when I noticed that the code calls a private method _substitute:with: on the _db attribute (which, by the way, isn't implemented by the SQLClientPool class).